Dan Carlin did a series of podcasts on this called 'Supernova in the east', talking about the how and why of Japan's approach to the war. I'm no great historian, but it seemed interesting to me. He quotes his sources and gives a pretty comprehensive overview of the figures involved and the ideologies that drove them. It's a good listen, each episode is around 5 hours long, but they're well laid out and it's easy to pick up from where you stopped.